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Over-heating triggered thermal runaway behavior for lithium-ion battery with high nickel content in positive electrode

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ENERGY 2021年 224卷 120072-120072页

作者： Wang, Haimin Shi, Weijie Hu, Feng Wang, Yufei Hu, Xuebin Li, Huanqi Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The thermal abuse of high specific energy NCM811 lithium-ion power battery in the process of use or safety test was simulated by winding resistance wire heating method, and local heating and uniform heating were carried out to trigger a thermal runaway. When thermal runaway triggered by uniform heating, the safety valve is opened timely and only open flame occurred without explosion, it did not cause the internal short circuit, and the safety valve was not damaged. However, when thermal runaway triggered by the local heating method, it caused a serious internal short circuit, the released electrolyte and other material burned violently and exploded, and the safety valve was completely damaged. In this process, a thin film heat flux sensor is also used to quantify the surface heat flux during thermal runaway, which could provide the test method and calculation basis for the thermal management design. The experimental results were also compared with those of NCM111, NCM 532 and NCM 622 batteries, the results revealed that increase of nickel content in positive electrode would also increase the degree of damage when a TR triggered by local heating method. (c) 2021 Elsevier Ltd. All rights reserved.

关键词： Lithium-ion battery NCM811 Thermal runaway Uniform heating Local heating heat flux

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High-power charging strategy within key SOC ranges based on heat generation of lithium-ion traction battery

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JOURNAL OF ENERGY STORAGE 2023年 72卷

作者： Wang, Haimin Wang, Chuanwei Jiang, Chenglong Zhou, Jiangang Liu, Wenqin Ji, Zhiyuan Meng, Guodong Zhao, Feng Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China China Automot Technol & Res Ctr Co Ltd Tianjin 300300 Peoples R China Dongfeng Commercial Vehicle Co Ltd Dongfeng Commercial Vehicle Tech Ctr Wuhan 430056 Peoples R China

A high-power charging strategy is proposed, which considers charging time and current as constraints, and minimizes heat generation as the optimization objective. Due to the minimal fluctuation of the internal resistance measured by the Hybrid Pulse power Characteristic (HPPC) method in the range of 20 % SOC to 80 % SOC, it is selected as the optimal range for high-power charging. Within this key SOC range, six stages were divided at equal intervals of 10%SOC. The temperature rise at charging rates of 1.0C to 3.0C is measured to form a threedimensional matrix of SOC, charging rate, and temperature, and the random value iteration method is used to find the optimal solution. The characteristic of this strategy is to segment and combine different high powers, and match Stage1 with higher charging power during the initial stage of low battery temperature, thereby effectively controlling the maximum temperature rise of the battery. In an experiment conducted at an ambient temperature of 25 degrees C, it was found that the performance was improved by using an optimized charging strategy compared to a constant current constant voltage (CC-CV) charging rate of *** maximum temperature decreased from 48.7 degrees C to 45.3 degrees C, and the charging time reduced from 1196 s to 1181 s. The charging capacities were 2749.6 mAh and 2732.4 mAh, with a slight increase in loss of 0.63 %. The heat generation decreased from 1413.1 J to 1662.9 J, a relative reduction of 15.02 %. In addition, the experiments verified that the charging strategy was also suitable for ternary lithium batteries and lithium iron phosphate batteries.

关键词： Traction battery High-power charging Thermal characteristics Charging strategy optimization

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Different pathways for methane hydrate nucleation and crystallization at high supercooling: Insights from molecular dynamics simulations

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JOURNAL OF MOLECULAR LIQUIDS 2021年 328卷 115466-115466页

作者： Liu, Ni Liu, Tingsong Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Natural gas hydrates are potential energy sources in the future, and thus it is important to understand its microscopic formation process. In this study, fourteen molecular dynamics (MD)trajectories were performed using the all-atom models by direct molecular dynamics simulations to investigate the nucleation and crystallization of methane hydrate from two-phase system of methane and water at T = 250 K and P = 50 MPa. Due to the strong interaction parameters used between water and methane in this study, methane molecules from gas phase can quickly enter the water phase to form supersaturated solution in the initial stage, increasing the probability of nucleation and the formation rate of hydrates. It was found that the hydrate nucleation and growth rate were slow in the initial configurations with the low-content methane, which is more conducive to the formation of crystalline hydrate. In configurations with low-content methane, sI crystal domains, sII crystal domains and polycrystalline structures with the coexistence of sI-like and sII were observed obviously in three trajectories. Our simulated results show that, at high supercooling, methane and water can still directly form crystalline methane hydrate. (C) 2021 Elsevier B.V. All rights reserved.

关键词： Methane hydrate Molecular dynamics simulation Crystallization

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Study on viscosity characteristics of CO₂-ionic liquid mixture used for compression-absorption refrigeration systems

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JOURNAL OF MOLECULAR LIQUIDS 2021年 337卷 116240-116240页

作者： Li, Kun Wu, Weidong Peng, Li Zhang, Hua Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

To provide a suitable absorbent for the carbon dioxide (CO2) compression-absorption refrigeration (CAR) system and promote the development of this system, the viscosities of CO2 + 1-ethyl-3-methylimidazo lium tris(perfluoroethyl)trifluorophosphate ([emim][FAP]) and CO2 + 1-hexyl-3-methylimidazolium tris (perfluoroethyl)trifluorophosphate ([hmim][FAP]) mixtures at vapor-liquid equilibrium were measured within the temperatures of 303.15-343.15 K and pressures of 1-10 MPa. The effects of CO2 solubility, pressure, temperature and ionic liquid structure on the mixture viscosity were investigated. The results showed that the mixture viscosity decreased with the increase of pressure and temperature. The longer the cationic alkyl chain of ionic liquid was, the larger the viscosities of ionic liquid and the corresponding mixture after absorbing CO2 were. But the mixture viscosity was less affected by the ionic liquid structure with the increase of temperature and pressure. The dissolution of CO2 could effectively reduce the mixture viscosity, to below 5.5 cP at most. Considering the CO2 absorption performance of ionic liquid and the viscosity of corresponding mixture, [hmim][FAP] is more suitable for the CO2 CAR system. In addition, to accurately predict the mixture viscosity within a certain working conditions for subsequent theoretical research of this system, an improved Grunberg equation was obtained by correlating the measured data and introducing the pressure factor. The overall average relative deviation between the calculated and measured data was 9.33%. The equation can be used to calculate the viscosity of the above CO2-ionic liquid mixtures. (C) 2021 Elsevier B.V. All rights reserved.

关键词： Carbon dioxide (CO2) Ionic liquids Compression-absorption refrigeration (CAR) CO2 solubility Viscosity

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Impacts of Gurney flap and solidity on the aerodynamic performance of vertical axis wind turbines in array configurations

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ENERGY 2021年第PartA期215卷 118915-118915页

作者： Ni, Lulu Miao, Weipao Li, Chun Liu, Qingsong Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

To improve the overall performance of VAWT farm configurations, the impacts of Gurney flap (GF) and the parameter of solidity on the performance of VAWTs in three-turbine arrays are investigated via computational fluid dynamics (CFD) simulations after a validation of computational model using experimental data in the present study. The results indicate that with the tip speed ratio (TSR) of the upstream pairs of VAWTs in array staggered configurations increasing, the flow velocity through the gap is higher and the upstream pairs of VAWTs achieve higher power output at high TSR compared to an isolated turbine. Then, the addition of GF on the upstream pairs of VAWTs can achieve higher flow velocity through the gap compared to the upstream clean coupled VAWTs, which is beneficial to the power output of downstream rotor. The downstream turbine in the configurations which consists of three GF-VAWTs achieves the best aerodynamic performance at TSR < 3.1, and at TSR = 2.51, this downstream rotor enhances the maximum average torque by 36.5% and 24% in comparison with the isolated clean turbine and the isolated GF-turbine respectively. Moreover, the downstream VAWT in array configurations with each solidity obtains higher power extraction than the isolated counterpart at overall TSR. At TSR = 2.27, the downstream rotor with a chord length of 123.5 mm achieves the increment of 23.1% in comparison with isolated counterpart. (c) 2020 Elsevier Ltd. All rights reserved.

关键词： CFD Gurney flap Solidity Aerodynamic performance Array configurations VAWT

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Ash formation characteristics in co-combusting coagulation sludge and Zhundong coal

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FUEL 2022年 311卷 122571-122571页

作者： Zheng, Liangqian Jin, Jing Liu, Zhongyi Kou, Xuesen He, Xiang Shen, Long Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Shanghai Power Equipment Res Inst Co Ltd Shanghai 200240 Peoples R China Shanghai Songshen Wastewater Treatment Plant Co L Shanghai 201615 Peoples R China

The co-combustion of coagulation sludge (CS) and Zhundong coal (ZDc) can simultaneously convert waste to energy and mitigate fouling and slagging problems during circulating fluidized bed (CFB) combustion of ZDc. In order to explore the ash forming characteristics after blending CS with ZDc, the ash melting curve method quantified the real-time ash fusion characteristics, and alkali metal sodium was analyzed. The results revealed that the ash fusion process of ZDc was divided into two stages. During the first stage, shrinkage was caused by the release of Na and the low temperature eutectic of Na2SO4 and CaSO4. The aluminosilicates in CS effectively decreased the release of alkali metal sodium and inhibited the low temperature eutectic, so the shrinkage rate of ZDc ash was effectively decreased by blending CS during the first stage. During the second stage of ZDc ash shrinkage, the ash shrinkage temperature decreased and the shrinkage rate increased by blending CS. It was attributed that the iron salts in the blends generated low melting point substances such as SiO2-Al2O3-Fe2O3 (MP: 1073 degrees C), which caused the blends ash to begin to shrink at around 1000 degrees C. As the blending ratio increased, iron-bearing minerals formed low temperature eutectic with the minerals previously produced, resulting in the rapid melting of the blends ash at around 1200 degrees C. In connection with the sodium retention and the ash melting curve, ash formation characteristics were optimized by blending CS with ZDc. The co-combustion of CS and ZDc is suitable for the boiler that operation temperature under 1000 degrees C.

关键词： Coagulation sludge Co-combustion Zhundong coal Ash fusion characteristics Alkali metals retention

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Thermal Stress in a Circular Nano-Inhomogeneity

SSRN

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SSRN 2022年

作者： Huang, Haojie Xing, Shichao Song, Kun School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China School of Energy and Power Engineering Shanghai Key Laboratory of Power Enegy in Multiphase Flow and Heat Transfer Shanghai China Key Laboratory of Construction Hydraulic Robots of Anhui Higher Education Institutes Tongling University Tongling244061 China School of Mechanical and Power Engineering Nanjing Tech University 30 Puzhu South Road Jiangsu Nanjing China

The thermal stress of nanocomposites is worth studying in that the extreme stress affects its reliability. In this paper, we propose a set of interfacial conditions to simulate the interfacial phonon scattering and interfacial elasticity in the nanocomposite, and obtain closed-form solutions for the thermal-elastic fields around the circular nano-inhomogeneity. The results show that the interfacial thermal stress within matrix is more sensitive to interfacial phonon scattering than that in the nano-inhomogeneity, while the size change of inhomogeneity has greater impact on the stress of the nano-inhomogeneity than that of the matrix. In view of the significant effects of thermal conductivities and thermal expansion coefficients on the thermal stress around inhomogeneity, the maximum von Mises stress is reduced up to three orders of magnitude by adjusting these parameters. More importantly, the thermal stresses within matrix and inhomogeneity can be respectively designed as "zero" even though the nanocomposite is subjected to a large thermal loading, which is viewed as an update mechanism of "neutral inhomogeneity". Our work provides guidance for the design of nanocomposites and has important potential applications. © 2022, The Authors. All rights reserved.

关键词： Thermal stress

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Characteristics of CO₂-ionic liquids/PEG200 as new working pairs for absorption-compression refrigeration system

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JOURNAL OF MOLECULAR LIQUIDS 2021年 340卷 116840-116840页

作者： Yang, Yingying Shen, Zhonghua Wu, Weidong Wang, Li Yang, Qiguo Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Absorption-compression refrigeration system using CO2-Ionic Liquids (ILs) as working pairs could avoid the high operating pressure in transcritical CO2 refrigeration cycle. This work proposed using PEG200 as the additive to improve the physical properties of the pure ILs, making the absorption-compression refrigeration system being more efficient and less corroded. The effects of PEG200 on the CO2-ILs absorption and desorption, the viscosity and the corrosion behavior on stainless steel were investigated experimentally. Results show that PEG200 has positive effect on these key parameters at temperature of 293.15 K to 343.15 K and pressures up to 10.0 MPa. The addition of PEG200 to [emim][FAP] could increase the CO2 solubility by 10.17% maximally, reduce the viscosity by 24.43% maximally, and accelerate the desorption rate. The CO2 solubility increases with the pressure increasing, and decreases with the temperature increasing. The viscosity of the mixed solvent decrease with the increase of the temperature and pressure. The addition of PEG200 to [emim][Tf2N] effectively weakens the corrosion on the 316L stainless steel, the corrosivity of ILs/PEG200 is less than that of the pure ILs. This work shows ILs with PEG200 added have better physical properties as the CO2 absorbent, providing a new approach of selection for CO2 absorption. (C) 2021 Elsevier B.V. All rights reserved.

关键词： CO2 absorption Ionic liquids [emim][FAP] [emim][Tf2N] PEG200

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Comprehensive study on sensitive parameters for chiller fault diagnosis

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ENERGY AND BUILDINGS 2021年 251卷 111318-111318页

作者： Gao, Y. Han, H. Ren, Z. X. Gao, J. Q. Jiang, S. X. Yang, Y. T. Univ Shanghai Sci & Technol Energy & Power Engn Coll Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

For the fault diagnosis of a building chiller, the selection of suitable features/parameters is potentially more critical than the selection of diagnosis methods. This study explores the sensitive parameters for the seven typical faults in chillers by performing global sensitivity analysis (GSA) based on a Random Forest (RF) meta-model, and proposes a novel hybrid feature screening strategy of cascade feature cleaning and supplement (CFCS) based on correlation analysis and experience. Compared with the traditional experience-based selection, the proposed methods can enable an insight from all dimensions;hence reduce the number of sensors significantly while retaining as much useful information as possible. The results show that the fourteen (SPCS-2 set) or nine parameters (SPDM-set) screened out from the original 64 parameters have an excellent indication to the seven faults, with the diagnosis accuracy reaching 99.67% and 99.79%, respectively. The generalization performance and diagnostic reliability of the feature sets has also been verified under different diagnosis methods. Besides, it is demonstrated that the parameters of lubricating oil exhibit an immediate and salient indication to the system status, more significant for fault diagnosis than those of refrigerant. Therefore, sensors for oil parameters are recommended to be installed for an early recognition of faults. (C) 2021 Elsevier B.V. All rights reserved.

关键词： Sensitivity analysis Correlation analysis Refrigeration system Fault detection Refrigerant leakage

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Molecular dynamics simulations on formation of CO₂ hydrate in the presence of metal particles

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JOURNAL OF MOLECULAR LIQUIDS 2021年 331卷 115793-115793页

作者： Liu, Ni Zhu, Hanqi Zhou, Jiali Yang, Liang Liu, Daoping Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Understanding and controlling the growth of CO2 hydrates is critical for a variety of industrial applications, such as sequestration of greenhouse gases. Due to the excellent physical and chemical properties, metal nanoclusters are widely used as additives in hydrate experiments. However, little is known about the molecular mechanism of this process. In this study, molecular dynamics (MD) simulation was performed at 260 K and 30 MPa by adding different types of metal particles (Cu, Fe and Ag) and different mass fractions (0.2 wt%, 0.5 wt%, 0.8 wt%, 1.0 wt% and 1.3 wt%) to study the growth kinetics of the CO2 hydrate system containing pre-placed hydrate crystal cells. Simulation results showed that the presence of these metal particles has a mixed effect on the growth kinetics, and the extent of the effect seems to varies with different additives and also with the concentration of the metal particles used. It was observed that Cu particles had the most obvious promoting effect on hydrate growth. When the mass fraction of Cu particles was between 0.2 wt% and 1.0 wt%, the rate of hydrate formation increased, especially at the mass fraction of 1.0 wt%. The growth rate of CO2 hydrate was almost 50% higher than that of pure water system at this concentration. In addition, Fe particles had a medium effect on promoting CO2 hydrate growth. Ag particles had no obvious effect on CO2 hydrate growth. Results show that the addition of metal particles with high specific surface areas greatly increases the mass and heat transfer among the gas, liquid and hydrate phases, which is conducive to the growth of CO2 hydrate. (C) 2021 Elsevier B.V. All rights reserved.

关键词： CO2 hydrate Formation Molecular dynamics simulation Metal particles

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